Ice Land by Betsy Tobin

Iceland, AD 1000 Freya knows that her people are doomed. Warned by the Fates of an impending disaster, she must embark on a journey to find a magnificent gold necklace, one said to possess the power to alter the course of history. But even as Freya travels deep into the mountains of Iceland, the country is on the brink of war. The new world order of Christianity is threatening the old ways of Iceland's people, and tangled amidst it all are two star-crossed lovers who destiny draws them together - even as their families are determined to tear them apart